"I thought: this day and age, there's a lot of women doing this. But it's very rare," said Nancie Weston, who founded the company in 2012. "Just being a startup and having a patented product is so rare, and then being a woman - you just don't see that."

Weston once worked in sales for a filter company, but saw a need for a portable, practical, stylish water bottle that would filter out bacteria and be earth-friendly. Several years, more than a dozen engineers, and 42 models later, Weston had a prototype she thought might work.

"I took (the original idea) to the company and they said, 'nope. Can't be done.' Went to 12 other engineers and they said, 'no, it can't be done,' " Weston said, of the process. "It was one of those things that I felt real passionate about. Now I can make a difference."

Weston is now one of four employees who work out of an old brick building that was once a pharmacy. In true startup fashion, the company's chief operating officer also handles demos, among other things.

"Everyone wears a million hats and I wear about 300,000 of them," joked Travis Merrigan.

Merrigan showed off the bottle's filter Monday, which works like a French press. An outside container holds water, and an interior container is pressed through it, purifying the water as it goes.

The cup filters 16 ounces of water in about 15 seconds, Merrigan said, and takes out 99.99% of odor and bacteria. An optional purifier can be used to filter out viruses, especially for visitors to developing countries.

"Travelers are really tired of having to go to foreign countries and buy bottled water. You think of a two-week trip to a tropical place where you're sweating a lot. You're drinking gallons of water a day," Merrigan said. "I used it exclusively for two weeks in China and I was fit as a fiddle."

Grayl has been for sale for about five months, Weston said, with about 3,000 cups sold so far, online and at REI stores. It retails for $69.95.

"I can't even go into a restaurant anymore because I've turned into a water snob," said Weston, laughing. "Not a coffee snob, but a water snob."